U.S. patent application number 14/449508 was filed with the patent office on 2015-02-05 for dust separation from the crude gas of an entrained flow gasifier.
The applicant listed for this patent is SIEMENS AKTIENGESELLSCHAFT. Invention is credited to Frank HANNEMANN, Manfred SCHINGNITZ.
Application Number | 20150033627 14/449508 |
Document ID | / |
Family ID | 52341925 |
Filed Date | 2015-02-05 |
United States Patent
Application |
20150033627 |
Kind Code |
A1 |
HANNEMANN; Frank ; et
al. |
February 5, 2015 |
DUST SEPARATION FROM THE CRUDE GAS OF AN ENTRAINED FLOW
GASIFIER
Abstract
A multistage gas washing system is applied for dust separation
from crude gases of entrained flow gasification of pulverized fuels
under pressures up to 10 MPa and temperatures which are greater
than the melting point of the fuel ash. A first stage comprises a
modified quenching system and a downstream washing column, which
operates as a bubble column. A second washing stage comprises one
or more Venturi washers connected in series. A third washing stage
comprises multiple high-pressure atomization units of washing
water, a partial condenser for cooling the crude gas by 1 to
15.degree. C. with condensate formation, and a separation column,
which is equipped with washing surfaces and a plastic-coated
demister.
Inventors: |
HANNEMANN; Frank; (Freiberg,
DE) ; SCHINGNITZ; Manfred; (Freiberg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SIEMENS AKTIENGESELLSCHAFT |
Munchen |
|
DE |
|
|
Family ID: |
52341925 |
Appl. No.: |
14/449508 |
Filed: |
August 1, 2014 |
Current U.S.
Class: |
48/90 ;
48/128 |
Current CPC
Class: |
C10K 1/101 20130101;
C10J 3/84 20130101; C10J 2300/093 20130101; C10J 3/485
20130101 |
Class at
Publication: |
48/90 ;
48/128 |
International
Class: |
C10J 3/84 20060101
C10J003/84 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2013 |
DE |
102013215120.9 |
Claims
1. A multistage crude gas washing system having a high degree of
separation of dust during the production of crude gas for an
entrained flow gasification plant for the reaction of ash and slag
forming fuels comprising: an entrained gas flow gasification plant
configured for operating under pressure up to 10 Mpa and
temperatures up to 1900.degree. C. a first crude gas washing stage
having a quencher and being configured for coarsely purifying crude
gas that had been generated, the first stage including injecting
devices for injecting water into the crude gas been generated for
coarsely purifying the crude gas, cooling the crude gas to a
temperature between 150 and 250.degree. C. and saturating the crude
gas with water vapor; a washing column following the quencher in a
path of the crude gas coarsely purified in the quencher, the
washing column having a bottom part configured for having a water
bath in the bottom part, and the washing column is configured to
cause the crude gas to flow through the water bath as a bubble
column; a second crude gas washing stage following the washing
column and the crude gas flows through a second crude gas washing
stage; the second crude gas washing stage including at least one
Venturi washer for the crude gas; a washing water separator
downstream in the path of the crude gas from the at least one
Venturi washer and configured for separating washing water from the
crude gas flow; a third crude gas washing stage connected for
following the water separation and for receiving crude gas from the
water separator, and a crude gas discharge following the third
crude gas washing stage; the third crude gas washing stage having a
high-pressure injection nozzle configured for finely-dispersed
injection of washing water that is free of solid material into the
crude gas; and a demister following the third crude gas washing
stage.
2. The crude gas washing system as claimed in claim 1, wherein the
demister comprises a droplet separator.
3. The crude gas washing system as claimed in claim 2, further
comprising a separation column following the droplet separator in
the path of the washed crude gas, the separation column having a
plate column and a demister which are both arranged after the
droplet separator.
4. The crude gas washing system as claimed in claim 1, further
comprising: a partial condenser after the high-pressure injection
nozzle in the path of the crude gas, a further high-pressure
injection nozzle following the condenser in the path of the crude
gas and configured for finely-dispersed injection of solids-free
washing water into the crude gas; and a separation column following
the further high-pressure injection nozzle in the path of the crude
gas, the separation column having a plate column therein; and, a
separate demister in the plate column.
5. The crude gas washing system as claimed in claim 3, wherein the
droplet separator includes washing surfaces therein.
6. The crude gas washing system as claimed in claim 1, further
comprising the high-pressure injection nozzle of the third crude
gas washing stage is supplied with water and is configured to
inject water in quantities and temperatures selected such that the
crude gas experiences a cooling of 1 to 15.degree. C.
7. The crude gas washing system as claimed in claim 6, further
comprising a discharge for crude gas from the quencher; a hood
positioned and configured for covering the crude gas discharge from
the quencher; and water spraying nozzles in the quencher under the
hood.
8. The crude gas washing system as claimed in claim 7, further
comprising a partition wall protruding from below into a volume in
the quencher enclosed by the hood.
9. The crude gas washing system as claimed in claim 7, wherein the
hood extends around an entire circumference of the quencher.
10. The crude gas washing system as claimed in claim 1, wherein the
at least one Venturi washer includes a throat which is
variable.
11. The crude gas washing system as claimed in claim 1, further
comprising a further injection nozzle configured for receiving and
injecting washing water such that the washing water is injected
into the path of the crude gas between the crude gas discharge from
the quencher and the washing column.
12. The crude gas washing system as claimed in claim 1, wherein the
system is configured to separate carbon black from the entrained
flow and into water, and configured so that discharge condensate
from the crude gas and the carbon black water are supplied again to
the washing stages after processing in the system.
13. The crude gas washing system as claimed in claim 1, further
comprising the demister is coated with PTFE.
14. The crude gas washing system as claimed in claim 1, further
comprising the demister is coated with a Teflon compound.
15. A method of washing a crude gas in an entrained-flow
gasification plant for the reaction of ash and also slag-forming
fuels, under a pressure of up to 10 MPa and a temperature up to
1900.degree. C., the method comprising: in a first crude gas
washing stage, passing the generated crude gas through a quencher
and coarsely purifying the generated crude gas in the quencher by
injecting water in the crude gas in excess of water that is
required, and the injecting of water also cooling the crude gas to
a temperature between 150 and 250.degree. C. and saturating the
crude gas with water vapor; supplying the crude gas leaving the
quencher to a washing cloumn, wherein the washing column is
configured to hold a water bath in a bottom part thereof; flowing
the crude gas through the water bath as a bubble column; following
the washing column, flowing the crude gas through a second crude
gas washing stage and through at least one Venturi washer in the
second stage; and following the at least one Venturi washer,
flowing the crude gas through a downstream washing water separator
for the crude gas that has passed the at least one Venturi washer;
conducting the crude gas leaving the second crude gas washing stage
through a third crude gas washing stage, in the third crude gas
washing stage, injecting a finely-dispersed injection of solid-free
washing water through a high-pressure nozzle into the crude gas and
then into a demister following the third crude gas washing
stage.
16. The method of claim 15, further comprising after spraying with
the high-pressure injection nozzle in the third crude gas washing
stage, flowing the crude gas through a partial condenser, followed
by a further high-pressure injection nozzle for finely-dispersed
injection of solid-free washing water into the crude gas, and
followed by passing the crude gas through a separation column which
includes a plate column and a separate demister.
17. The method of claim 15 further comprising in the second stage,
supplying washing water to the high-pressure injection nozzle of
the third washing stage in such quantity and at such temperature
that the crude gas experiences a cooling by 1 to 15.degree. C.
18. The method of claim 15, further comprising the spraying of
washing water into the crude gas and the supplying of crude gas
washing the injected water and condensate from the crude gas and
producing carbon black water, and then discharging the carbon black
water; and supplying the discharged condensate from the crude gas
and supplying the washing waters from the system again to the
washing stages after processing thereof in the system.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the priority of German Patent
Application No. 102013215120.9, filed Aug. 1, 2013, the contents of
which are incorporated by reference herein.
TECHNICAL FIELD
[0002] The invention relates to a multistage crude gas washing
system having a high degree of separation of particles, in
particular fine dust, during the production of crude gas rich in CO
and H.sub.2 in an entrained flow gasification plant by reaction of
ash, but also slag-forming fuels, under pressures up to 10 MPa and
temperatures up to 1900.degree. C.
TECHNICAL BACKGROUND
[0003] Pulverized fuels are understood to include finely-ground
coals of different degrees of carbonization, dusts made of
biomasses, products of the thermal pretreatment such as coke, dried
products by way of "torrefaction", and fractions having high
calorific value from municipal and industrial residual materials
and waste materials. The pulverized fuels can be supplied as a
gas-solid suspension or as a liquid-solid suspension to the
gasification. The gasification reactors can be provided with a
cooling screen or with a refractory lining, as disclosed in the
patents DE 4446803 and EP 0677567. According to various systems
introduced into technology, the crude gas and the molten liquid
slag can be discharged separately or jointly in this case from the
reaction chamber of the gasification device, as described in DE
19718131. A comprehensive description of the overall technology is
found in J. Carl, P. Fritz, NOELL-KONVERSATIONSVERFAHREN,
EF-Verlag, 1996, pages 25-53. Entrained flow gasification causes,
as a result of the fuel particles, which are ground as fine as
dust, and shorter reaction times in the gasification chamber, an
increased dust fraction in the crude gas. This flue dust consists,
in dependence on the reactivity of the fuel, of carbon black,
unreacted fuel particles, and fine particles of slag and ash. The
size varies between coarse particles having a diameter greater than
0.5 mm and fine particles having a diameter up to 0.1 .mu.m. The
separability of the particles from the crude gas is dependent on
this diameter, but also on the composition thereof. Fundamentally,
a differentiation can be made between carbon black and ash, on the
one hand, and slag particles, on the other hand, wherein carbon
black particles are generally smaller and more difficult to
separate from the crude gas. Slag particles have a higher density
and therefore a better separability, but in contrast thereto have a
higher hardness and therefore an erosive effect. This results in
increased wear in the classifying separators and lines which
conduct crude gas, which can cause safety-relevant leaks and
service life restrictions.
[0004] The previous prior art is documented in the patent DE 10
2005 041 930 and also in "Die Veredelung von Kohle [The Refinement
of Coals]", DGMK, Hamburg, December 2008, chapter "GSP-Verfahren
[GSP Method]" pages 537-553, particularly in FIGS. 4.4.2.4.13 and
4.4.2.9.1. Accordingly, the gasification crude gas leaves the
gasification chamber jointly with the slag formed from the fuel ash
at temperatures of 1300-1900.degree. C. and is cooled in a
downstream quenching chamber by injection of excess water and freed
of the slag and, to a small extent, of entrained dust. The further
dust removal is performed in two Venturi washers connected in
series, wherein the second washer has an adjustable throat to be
able to keep the velocity in the throat constant even in the event
of changing crude gas quantity and therefore to ensure a uniform
velocity for the entrained dust. The gas purification was conceived
for dust quantities up to 2 g/m.sup.3 under normal conditions and
is intended to achieve a dust quantity of 1-3 mg/m.sup.3 under
normal conditions at the outlet, which is necessary for
disturbance-free operation of the downstream plants, such as CO
conversion, synthesis, or gas turbines. To remove fine dusts,
particularly of salt spray, a partial condenser is operated, in
which the crude gas is cooled by 1-15.degree. C., wherein the
condensed water precipitates on the salt particles in particular
and is removed from the crude gas stream by separation of the water
droplets. For dust quantities greater than 2 g/m.sup.3 under normal
conditions, this arrangement consisting of two Venturi washers and
a partial condensation step is only partially adequate or is
inadequate and can result in substantially higher dust
concentrations in the intake of the CO conversion and also
increased erosion in the Venturi washers and furthermore in soiling
and blocking in the partial condenser and the downstream
systems.
SUMMARY OF THE INVENTRION
[0005] Proceeding from this prior art, it is the object of the
invention to provide a gas purification system for an entrained
flow gasification plant, which has a high separation rate of
particles, in particular of fine dust, which, with a reliable
operating mode, takes into consideration the different ash contents
and ash properties of the fuels, and which has a high
availability.
[0006] This object is achieved by a crude gas washing system having
the features of the first invention.
[0007] To design the gasification plant for higher dust
concentrations, consisting of coarse and fine particles, a
selective separation of the particles is used. A combination of
coarse-fine separators is proposed, which, in a first purification
step, separates the coarse and particularly erosive particles in a
robust and possibly multistage washing stage. This firstly has a
quenching chamber, into which excess water is injected in finely
dispersed form and in which, in addition to the cooling of the
crude gas, a separation of very coarse dust particles occurs
simultaneously. This is assisted by the arrangement of a hood over
the crude gas discharge, which, in conjunction with a partition
wall protruding downwards into the hood, forces the gas stream into
a triple direction change and is additionally sprayed to avoid
incrustations. Subsequently, the crude gas flows through a washing
column having an immersion pipe, where it rises upward as a bubble
column in the accumulated washing liquid. Due to the low velocity
in the gas chamber located above it, dust-loaded water droplets are
not entrained and fall back into the bubble column. All particles
>10 .mu.m are completely separated via this purification step.
Smaller particles are separated in a following purification step,
which consists of one or two successive Venturi washers. To also
separate ultrafine particles <1 .mu.m, the crude gas experiences
direct cooling, but also indirect cooling of 1-15.degree. C. by
high-pressure injection of water 18, 20 or in a heat exchanger 19,
respectively. The water loaded with fine dust and also condensate
is subsequently separated from the crude gas in a fine droplet
separator and returns into the water circuits. Ultrafine droplets
having a large surface area, which can also absorb very fine
particles, arise due to the high-pressure injection and the
cooling. The fine droplet separator 21 can be equipped with washing
surfaces 22 and is fitted in the top part with a coated demister
packing 23. To counteract the hazard due to soiling of the droplet
separator, it is coated using PTFE or a Teflon compound. Over 99.9%
of the particles can be separated by the described combination of
the mentioned cleaning stages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention will be explained hereafter to an extent
required for understanding on the basis of three figures and three
exemplary embodiments. In the figures:
[0009] FIG. 1 shows a technology for dust separation in a cascade
of quenching unit having hood, a washing column, two Venturi
washers, a high-pressure injection nozzle, a partial condenser, and
a fine droplet separator,
[0010] FIG. 2 shows a technology for dust separation in a cascade
of quenching unit having hood, a washing column, two Venturi
washers, a high-pressure atomization unit having demister-droplet
separator, and downstream fine droplet separator,
[0011] FIG. 3 shows a technology for dust separation in a cascade
of quenching unit having hood, a washing column, a Venturi washer,
and a high-pressure atomization unit having a demister-droplet
separator.
DESCRIPTION OF EMBODIMENTS
[0012] In the figures, identical reference signs identify identical
elements.
[0013] 80 Mg/h pulverized dust made of a lean coal are supplied to
an entrained flow reactor having a gross output of 500 MW, as shown
in FIG. 1, according to the principle of pneumatic conveying using
carbon dioxide as a carrier gas via the dust conveyor line 1 and
converted jointly with 45,000 m.sup.3/h oxygen under normal
conditions via line 2 in the gasification chamber 3 at temperatures
of 1650.degree. C. and a pressure of 4.5 MPa into a crude synthesis
gas. The gasification chamber 3 is delimited by a cooling screen 4.
The fuel ash is melted at the mentioned gasification temperatures
and largely applied to the cooling screen, runs downward, and
reaches the downstream quenching chamber 6 via the crude gas and
slag discharge opening 5. The crude gas quantity is 135,000
m.sup.3/h under normal conditions. The temperatures after the
quenching are between 150 and 250.degree. C., the crude gas is
saturated with water vapor. Not all of the fuel ash melted into
slag reaches the cooling screen 4, but rather a part is discharged
directly with the crude gas stream, so that the crude gas entrains
a dust content of approximately 2 g/m.sup.3 under normal
conditions, having the following grain size distribution:
TABLE-US-00001 mass particle fraction in size in .mu.m mass-% total
mass-% 0.2 98.3 approx. 35 0.25 95.9 0.315 92.4 0.4 87.4 0.5 79.7
0.63 65.7 approx. 35 0.8 49.7 1 40.6 1.25 35.6 1.6 33.6 2 32.2 2.5
31.2 5 30.7 10 30.5 approx. 30 16 30.2 50 30 100 25.9 400 21.1 1000
4.4 2500 0
[0014] Since this dust results in disturbances in subsequent
processes by way of erosion or deposits, a removal down to residual
contents <1 mg/m.sup.3 under normal conditions is necessary,
wherein the fine dust separation represents a special technological
demand. To fulfill the stated goal, a multistage gas washing system
is installed. The first stage comprises a modified quenching system
and a downstream washing column, which operates as a bubble column.
In the quenching chamber 6, crude gas and slag are firstly cooled
to 220.degree. C. and saturated with water vapor at the same time
by injection of excess water. The separation of coarse dust already
begins here due to a special modification of the quenching chamber
6. For this purpose, a hood having nozzles 9 is installed over the
crude gas discharge 11, wherein a partition plate protrudes from
below into the space enclosed by the hood. The crude gas leaving
the quencher is forced into a triple direction change, whereby a
further separation of particles occurs in conjunction with the
nozzles 9. The hood can be drawn over a part or the entire
circumference of the quenching chamber. Additional washing water
can be introduced after the crude gas discharge 11 via an injection
nozzle 10. Furthermore, the crude gas enters a washing column 12,
is immersed in the water bath 13, and is guided upward as a bubble
column into a free space at low crude gas velocity. In this first
gas washing stage, approximately 30 mass-% of the coarse dust in
the grain size range from 2500 to 10 .mu.m is removed from the
crude gas.
[0015] The second washing stage comprises a Venturi washing system,
in which a first Venturi washer 14 having a fixed throat and a
second Venturi washer 15 having a variable throat and water supply
16 are arranged.
[0016] The variable throat in the second Venturi washer 15 enables
it to react to varying crude gas quantities. In this second washing
stage, approximately 35 mass-% of the dust entrained in the crude
gas in a grain size range up to 0.6 .mu.m is separated.
[0017] In the third washing stage, the demanding fine dust
separation is managed, which places special demands on the
technology. For this purpose, solid-free washing water is injected
in ultrafine dispersed form before and after a partial condenser 19
by high-pressure injection nozzles 18 and 20, to wet the entrained
dust particles. The partial condenser 19 has the same task, in
which, by way of cooling of the crude gas saturated with water
vapor by 1 to 15.degree. C., approximately 3 to 10 m.sup.3/h water
vapor are formed with formation of similarly ultrafine droplets,
wherein the fine dust particles represent condensation seeds for
the water vapor and therefore the fine dust is incorporated in the
condensed water. To separate the dust-carrying droplets, the third
washing stage is terminated by a separation column 21, which is
fitted with a plate column 22 and a plastic-coated demister 23. The
crude gas, which is substantially freed of dust, leaves the
separation chamber 21 via the gas discharge 24 and subsequently
reaches further processes up to the generation of the final
product. The carbon black water 25 separated from all of the
washing stages and also the condensate and washing water 26 are
returned after a separation of the entrained solids in the circuit
back into the washing stages.
[0018] In an entrained flow gasification plant according to FIG. 2,
the dust fraction formed in the gasification chamber 3 during the
gasification of the fuel is dependent on various parameters. These
include fuel properties, such as its reactivity, the grain size
distribution, the ash content, the ash composition and therefore
the ash melting point, and also the toughness behavior of the slag
formed. The three-stage washing system is modified in consideration
of special fuel properties. In this example--having the same output
as above--a water-fuel suspension having a solid fraction of 60
mass-% is supplied to the gasification reactor via the slurry line
1a and converted with oxygen via line 2 in the gasification chamber
3 to form crude gas. The oxygen usage is increased to 53,000
m.sup.3/h under normal conditions by the entrained water fraction.
The gasification temperature is 1550.degree. C., and the pressure
is 4.5 MPa. A crude gas quantity corresponding to the predefined
output of 135,000 m.sup.3/h is also generated under normal
conditions. The first washing stage is identical to that in the
above example according to FIG. 1. The second washing stage is
restricted to one Venturi washer 14 having water supply 16 and a
water separator 17. The Venturi washer 14 is expediently equipped
with a variable throat for adaptation to occurring variations of
the generated crude gas quantity. A high-pressure atomization unit
18 having a droplet separator 27 as a demister follows after the
washing water separator 17, as the third washing stage, from which
an additional separation column 21 is connected downstream, which
is also equipped with a plate column 22 and a further
plastic-coated demister. The carbon black water discharge and also
the condensate and washing water discharge 25 and 26, respectively,
are incorporated in the water treatment and circulation
systems.
[0019] In an entrained flow gasification plant according to FIG. 3,
a water-fuel suspension is also gasified under the same conditions
as in the above example. The first and second washing stages
correspond to the illustration in the above exemplary embodiment
according to FIG. 2. The third washing stage is restricted to the
high-pressure atomization of washing water 18 and the droplet
separator 27 embodied as a demister. To condense out water vapor,
the washing water used in the high-pressure atomization unit 18 is
used with quantities and temperatures such that the crude gas
experiences a cooling by 1 to 15.degree. C. Carbon black water 25
and condensate and washing water 26 are also incorporated into the
water treatment and circulation systems.
[0020] The invention is also provided by a method for dust
separation from crude gases of entrained flow gasification of
pneumatically or hydraulically supplied pulverized fuels under
pressures up to 10 MPa and temperatures between 150 and 250.degree.
C. in the state of water-vapor saturation by a three-stage gas
washing system, in which [0021] the first stage consists of a
quenching system, in which a water-sprinkled hood having nozzles 9
is arranged over the crude gas discharge 11, followed by a washing
column 12, which has a water bath 13 in the bottom part, through
which crude gas flows in the form of a bubble column, [0022] the
second washing stage consists of one or more Venturi washers 17,
which are connected in series and have downstream separators 17,
[0023] the third washing stage consists of a partial condenser 19,
before and after which high-pressure atomization units 18 and 20
are arranged, and a separation column 21, which has a plate column
22 and a plastic-coated demister 23.
LIST OF REFERENCE NUMERALS
[0024] 1 dust conveyor line
[0025] 1a slurry line
[0026] 2 oxygen line
[0027] 3 gasification chamber
[0028] 4 cooling screen
[0029] 5 crude gas and slag discharge opening
[0030] 6 quenching chamber
[0031] 7 quenching water injection
[0032] 8 slag discharge
[0033] 9 hood having nozzles
[0034] 10 washing water injection nozzle
[0035] 11 crude gas discharge
[0036] 12 washing column
[0037] 13 water bath
[0038] 14 Venturi washer 1
[0039] 15 Venturi washer 2
[0040] 16 washing water
[0041] 17 washing water separator
[0042] 18 high-pressure atomization of washing water before partial
condenser 19
[0043] 19 partial condenser
[0044] 20 high-pressure atomization of washing water after partial
condenser 19
[0045] 21 separation column
[0046] 22 plate column
[0047] 23 coated demister
[0048] 24 gas discharge
[0049] 25 carbon black water discharge
[0050] 26 condensate and washing water discharge
[0051] 27 droplet separator as demister
* * * * *